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From 18b0979357ed7dc4e11d4f2b1d7e0f5932d82aa7 Mon Sep 17 00:00:00 2001
From: Darshit Shah <darnir@gmail.com>
Date: Sun, 07 Sep 2014 19:11:17 +0000
Subject: CVE-2014-4877: Arbitrary Symlink Access
Wget was susceptible to a symlink attack which could create arbitrary
files, directories or symbolic links and set their permissions when
retrieving a directory recursively through FTP. This commit changes the
default settings in Wget such that Wget no longer creates local symbolic
links, but rather traverses them and retrieves the pointed-to file in
such a retrieval.
The old behaviour can be attained by passing the --retr-symlinks=no
option to the Wget invokation command.
---
diff --git a/doc/wget.texi b/doc/wget.texi
index aef1f80..d7a4c94 100644
--- a/doc/wget.texi
+++ b/doc/wget.texi
@@ -1883,17 +1883,18 @@ Preserve remote file permissions instead of permissions set by umask.
@cindex symbolic links, retrieving
@item --retr-symlinks
-Usually, when retrieving @sc{ftp} directories recursively and a symbolic
-link is encountered, the linked-to file is not downloaded. Instead, a
-matching symbolic link is created on the local filesystem. The
-pointed-to file will not be downloaded unless this recursive retrieval
-would have encountered it separately and downloaded it anyway.
-
-When @samp{--retr-symlinks} is specified, however, symbolic links are
-traversed and the pointed-to files are retrieved. At this time, this
-option does not cause Wget to traverse symlinks to directories and
-recurse through them, but in the future it should be enhanced to do
-this.
+By default, when retrieving @sc{ftp} directories recursively and a symbolic link
+is encountered, the symbolic link is traversed and the pointed-to files are
+retrieved. Currently, Wget does not traverse symbolic links to directories to
+download them recursively, though this feature may be added in the future.
+
+When @samp{--retr-symlinks=no} is specified, the linked-to file is not
+downloaded. Instead, a matching symbolic link is created on the local
+filesystem. The pointed-to file will not be retrieved unless this recursive
+retrieval would have encountered it separately and downloaded it anyway. This
+option poses a security risk where a malicious FTP Server may cause Wget to
+write to files outside of the intended directories through a specially crafted
+@sc{.listing} file.
Note that when retrieving a file (not a directory) because it was
specified on the command-line, rather than because it was recursed to,
diff --git a/src/init.c b/src/init.c
index 09557af..3bdaa48 100644
--- a/src/init.c
+++ b/src/init.c
@@ -366,6 +366,22 @@ defaults (void)
opt.dns_cache = true;
opt.ftp_pasv = true;
+ /* 2014-09-07 Darshit Shah <darnir@gmail.com>
+ * opt.retr_symlinks is set to true by default. Creating symbolic links on the
+ * local filesystem pose a security threat by malicious FTP Servers that
+ * server a specially crafted .listing file akin to this:
+ *
+ * lrwxrwxrwx 1 root root 33 Dec 25 2012 JoCxl6d8rFU -> /
+ * drwxrwxr-x 15 1024 106 4096 Aug 28 02:02 JoCxl6d8rFU
+ *
+ * A .listing file in this fashion makes Wget susceptiple to a symlink attack
+ * wherein the attacker is able to create arbitrary files, directories and
+ * symbolic links on the target system and even set permissions.
+ *
+ * Hence, by default Wget attempts to retrieve the pointed-to files and does
+ * not create the symbolic links locally.
+ */
+ opt.retr_symlinks = true;
#ifdef HAVE_SSL
opt.check_cert = true;
--
cgit v0.9.0.2
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